I love this cake to pieces, but can't cook it where I live (elevation: 7000 feet.) It's based on a cake I had a lot in restaurants in the UK called "Fudge Cake," and the 'frosting' is a reflection of that. The main point of it is to use it to frost the cake, and then let it cool enough to let the (well, chocolate sauce) harden into a firm chocolate paste. Now, this sounds a bit silly, but the reason you want to cool it down is so that you can heat it back up. Seriously. This cake was always served hot, with the sauce pooling and seeping into the cake. It's marvelous, marvelous stuff, which is why I went to the trouble of trying to approximate it. As I mention down in the recipe, you can eat it cold, or you can just eat it immediately by pouring it over slices of cake. Cold is no fun and kind of goes against the whole entire point of not using a traditional frosting. Eating it immediately is appealing, but that's even more messy and also means it pretty much has to be eaten all at once, because there's no way to really frost it and save it after you've cut it up. (Well, you can, but it will never be as nice as if you did it properly in the first place).
The cream-cheese frosting is tasty and unusual. I've included it because the fudge one is a little more work, a lot more messy, and etc. So I've stolen the cream-cheese frosting from my friend Claire. It works surprisingly well with the chocolate cake. ( Chocolate cake )